Method for desulphurizing iron with molten calcium carbide



1946.. CROWE 2,409,020

METHOD FOR DESULPHURIZING IRON WITH MOLTEN CALCIUM CARBIDE Filed Dec. 8, 1943 IN VEN TOR.

famkmmim ATTORNEYS Pmmd Oct. 8, 194

UNITED STATES PATENT OFFICE METHOD FOR DESULPHUR IZING IRON WITH MOLTEN CALCIUIH CARBIDE John J. Crowe,

J., assignor to Air Reduction Company, Incorporated, New York,

. Y., a corporation of New York Application December 8, 1943, Serial No.

3 Claims.

This invention relates to the desulphurizing of metals such as iron to an improved method of introducing a de sulphurizing agent to molten metal and apparatus therefor.

As is well known, sulphur may be an undesirable element in iron and steel. Various methods of eliminating sulphur have been proposed, including the addition of solid calcium carbide (CaCz) to the molten metal.

The melting point of calcium carbide is approximately 2300 0., which is far above the temthe molten metal and combination with the sultion of the sulphur content of the metal.

Other objects and advantages of the invention will be apparent as it is better understood by reference to the following specification andthe accompanying drawing, in which Fig. 1 is a vertical sectional view of an apparatus suitable for the practice of the invention; and

are assists in causing seminate through the In carrying out the invention, I prefer to employ a melting receptacle for the carbide which and steel and particularly fioats upon the surface of the molten metal in a ladle or other suitable container. The carbide Cooling of the molten carbide container.

The required amount of carbide in lump form, approximately 6 pounds per pound of sulphur to be removed, is placed in the receptacle. such as sodium chloride may be added, if desired, cilitatethe reaction. The amount of flux, if any is employed, is not critical. then started to melt the carbide. carbide is mixed directly into the molten metal. The carbide reacts with sulphur in metal is thus reduced.

Referring to the drawing, 5 indicates an ingot mold or ladle of any suitable form and material recess 8 aifording a receptacle for the lumps of carbide 9. The receptacle has an opening ill at its bottom which is submerged in the molten metal and beneath the surface thereof which is exposed to the atmosphere.

Electrodes H are arranged in suitable supports [2 so that their ends are contiguous. Conductors I3 are connected to the electrodes and to a source of current. While two electrodes are preferred, it is apparent that any other arrangement may be employed in accordance with well understood principles of electric furnace construction.

moved will be separated in the slag to the surface of the molten metal.

Various changes may be made in the form and construction of the apparatus and in the procedure as described without departing from the invention or sacrificing the advantages thereof.

The term "substantially pure calcium carbide" is used in the appended claims to define commercial carbide and to distinguish from slags which contain calcium carbide dissolved in or cilispersed through other constituents of the s ag.

I claim:

1. In the desulphurizing of molten iron and steel, the steps which comprise confining commercially pure calcium carbide to a relatively small restricted area on the surface of a body of the molten metal, melting the calcium carbide by means of an electric arc, thereby introducing the molten calcium carbide into the body of molten metal beneath the surface thereof while the molten metal is in a state of agitation to cause desulphurization of the metal.

2. In the desulphurizing of molten iron and 2 4 steel, the steps which comprise confining commercially pure calcium carbide to a relatively small restricted area on the surface of the molten metal, melting the calcium carbide by means of an electric are, thereby causing the molten calcium carbide to diffuse into the molten metal and desulphurize the same.

3. In the desulphurizing of molten iron and steel, the steps which comprise confining commercially pure calcium carbide to a relatively small restricted area on the surface of the molten metal, melting the calcium carbide by an external source of heat, and introducing the molten carbide to the molten metal directly and beneath the surface thereof which is exposed to the atmosphere, whereby the molten calcium caused to difiuse into themolten metal and desulphurize the same.

' JOHN J. CROWE. 

